When making printed circuits, the starting material is an insulating support plate coated in copper on its front and back surfaces, and of thickness and dimensions that can vary from one circuit to another.
To perform various operations on the insulating support for the purpose of making a printed circuit, it is usually necessary for the printed circuit panel to be accurately plane while the operations are being performed. For example, this is necessary when performing punching operations on the panel to ensure that its holes are accurately located. It is also necessary when a conductor or other material is to be deposited on the insulating support, e.g. in a photoetching operation, in order to guarantee that the layer deposited by photoetching has exactly the right shape.
Documents DE 43 39092, U.S. Pat. No. 4,700,488, and DE 41 08846 describe machines for holding printed circuit panels that are based on engaging parallel margins of the panel.
However, in those machines, the means for taking hold of the margins of the panel are insufficient for guaranteeing that the panel is kept planar without any warping, particularly if the panel is of large dimensions and is also heavy.